Analysis of Glycols from Drinking Water and Seawater Using

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Analysis of Glycols from Drinking Water and Seawater Using ENVI-Carb Plus SPE and GC-FIDMichael Ye, K. K. Stenerson, W. R. Betz, M.J. KeelerExTech 2014

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Agenda

• Introduction

• Extraction method from water

• Quantitative evaluation of extraction method

• Extraction of “other” water matrices

• Conclusions


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Introduction• Glycols and glycol-ethers are used in a variety of

applications:• Antifreeze• Cosmetics • Foods• Coolants• Chemical dispersants• Emulsifiers

• Analysis of ethylene and propylene glycols is commonly done in ground water samples using US EPA Methods 8015 or 1671 (1,2).

• Ethylene glycol was included on the Drinking Water Contaminant Candidate List 3 Draft by EPA in 2008 (3).


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Introduction

• Propylene glycol and 2-butoxyethanol are contained in Corexit™ 9500 and Corexit™EC9527A oil dispersants respectively (4,5).

• Corexit™ 9500 was used extensively for oil spill in the Gulf of Mexico April 20, 2010.

• Using current methods, analysis for propylene glycol in seawater would require direct injection into a GC.

Corexit™ is a trademark of the Nalco Corp.


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The Current Method - Direct Aqueous Injection (DAI)

• Water has a high vapor volume• Requires low injection volume and/or high inlet pressure to

contain vapor cloud

• Poor peak shape• Especially early eluting compounds

• Affects detection and quantitation

• Presence of matrix (such as salt) in a sample could easily foul the GC inlet and/or column.


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1. 2-methoxyethanol 5. Ethylene glycol2. 2-ethoxyethanol 6. Diethylene glycol3. 2-butoxyethanol 7. Triethylene glycol4. Propylene glycol

8 10 12 14 16 18 20 22 24 26Time (min)

20

40

pA 4

5

6 73

Peaks 1 and 2 not detected

The Current Method- DAI10 ug/ml standard in deionized water


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Goals of New Method

• Eliminate direct aqueous injection (DAI) of samples for glycol analysis.

• Lower detection and quantitation levels.

• Use solid phase extraction to extract glycols from water matrices.• Achieve elution with an organic solvent

• Inject sample extract in organic solvent into GC


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8 10 12 14 16 18 20 22 24 26Time (min)

20

40

AU

3

2

1

67

4

5

If the injection could be made in methanol…10 ug/ml standard in methanol

pA


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Glycols and glycol ethers included in studyCAS # Structure Uses

2-methoxyethanol (methyl cellosolve)

109-86-4 Solvent, airplane de-icing solutions

2-ethoxyethanol (ethyl cellosolve)

110-80-5 solvent

2-butoxyethanol (butyl cellosolve)

111-76-2 Solvent, cleaning products, dispersants (Corexit™ 9527)

Ethylene glycol 107-21-1 antifreeze

Propylene glycol 57-55-6 Auto antifreeze, polymer precursor, dispersants (Corexit™ 9500)

Diethylene glycol 111-46-6 Organic synthesis, solvent, humectant, lubricant

Triethylene glycol 112-27-6 Solvent, plasticizer, aerosol disinfectant, chemical additive, gas dehydration

OHO CH3

CH3O

OH

OHO CH3

O H

O HCH 3

OHOH

OH OHO

OOOH

OH


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Extraction Method –Choice of extraction material

Glycols too hydrophilic to retain on reverse phase materialsCarbon materials exhibit size and shape selectivity ENVI-Carb™ Plus

• Microporous amorphous carbon molecular sieve – Open pore structure (presence of macro and mesopores)

allows better access to micropores• Surface is less hydrophobic than other types of carbons• Has a higher affinity for water than other carbons• Affinity for water helps draw analytes from aqueous solution into

its pore structure. • Elution of analytes is achieved by flooding the pores with a

solvent in which the analyte is soluble.


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Development of Extraction Method• Sample volume

• 5 ml size used for convenience.• Have not evaluated for larger volumes.

• Elution• Used organic solvent• 80% methanol/20% methylene chloride solvent composition • 2 ml elution volume• Elution in forward direction

• Comparison of different carbons• ENVI-Carb™: graphitized,nonporous • Coconut charcoal: irregularly shaped, microporous• ENVI-Carb™Plus: microporous, amorphous carbon molecular sieve – worked the best


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Extraction MethodComparison of different carbons

0

2

4

6

8

10

12

14

16

2-meth

oxye

thano

l2-

ethox

yeth

anol

2-bu

toxye

than

olpr

opyle

ne g

lycol

ethyle

ne glyc

oldie

thylen

e glyc

oltrie

thyle

ne gl

ycol

Am

t. R

ecov

ered

(ug/

ml)

ENVI-Carb Plus

ENVI-Carb

Coconut charcoal

Tube sizes:ENVI-Carb™Plus: 400 mg/1 mlENVI-Carb™: 500 mg/6 mlCoconut charcoal: 2 gm/6 ml mlml

Deionized water samples spiked at 10 ug/ml. Final extracts brought to FV=2 mL prior to analysis


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Final SPE Extraction Method

Extraction Cartridge

ENVI-Carb ™ Plus reversible cartridge, 1 ml/400 mg

Cartridge Conditioning

1 ml methylene chloride , 2 x 2 ml aliquots methanol, 3 ml dei. water

Sample 5 mL tap water spiked at 10 ug/ml

Sample extraction

5 ml sample, 5 mm Hg

Dry time 10 minutes, 10 mm Hg

Elution Cartridge in forward direction, 2 ml of methanol:methylene chloride, 80:20 (soak cartridge for 1 minutes prior to pulling through)

Preparation for GC analysis

Added methanol to bring sample to final volume of 2 ml and analyzed directly


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Column SPB-1000, 30 m x 0.25 mm I.D. x 0.25 µm

Oven 50 °C (1 min. or 2.5 min.), 8 °C/min. to 200 °C (12 min.)

Injector 220°C

Detector FID, 220 °C

Carrier gas Helium, 1.5 ml/min, constant flow

Injection 1 µL, splitless

Liner 4 mm ID, focus liner with taper (extracts)4 mm ID dual taper liner (DAI)

GC-FID Analysis Method


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Quantitative EvaluationExtraction at Different Concentrations

• Extracted deionized water spiked at concentrations from 1 to 50 ug/ml.

• The response of each compound was plotted against the spiked concentration.

• Responses plotted are absolute - i.e no internal standard correction was used.

• Excellent linearity was obtained for each compound.

•Calculated % recovery by external standard quantitation against standards in methanol.


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Quantitative EvaluationConcentration spiked vs. analyte response

R2 = 0.9988

R2 = 0.9972

R2 = 0.9991

R2 = 0.9996R2 = 0.9999

R2 = 0.9999

0100200300400500600700800900

0 10 20 30 40 50 60Spike conc. (ug/ml)

Peak

are

a

2-methoxyethanol 2-ethoxyethanol 2-butoxyethanol propylene glycolethylene glycol diethylene glycol triethylene glycol


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Absolute recovery from deionized water samplesSpike level (ug/ml): 1 2 5 10 20 502-methoxyethanol 113% 103% 94% 96% 97% 101%2-ethoxyethanol 106% 96% 90% 92% 90% 92%2-butoxyethanol 113% 103% 97% 98% 97% 99%propylene glycol 123% 101% 94% 94% 96% 99%ethylene glycol 78% 55% 43% 40% 43% 45%diethylene glycol 132% 94% 82% 82% 84% 89%triethylene glycol 152% 97% 77% 82% 84% 93%

Quantitative Evaluation

Possibly below quantitation limit of method


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• Spiked tap water at 2 ug/ml

• 7 replicates extracted in 2 separate batches on separate days•The average recovery for all compounds except ethylene glycol was >90%.

• Ethylene glycol is the smallest and most hydrophilic of the analytes.

• Ethylene glycol was detected in un-retained water sample after extraction through the cartridge.

• % RSD values < 10% for all compounds except ethylene glycol (16%).

Recovery and Reproducibility Evaluation-Extraction Method


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Absolute recovery from tap water spiked at 2 ug/ml, n=7

date extracted 13-Jul 13-Jul 13-Jul 17-Aug 17-Aug 17-Aug 17-Aug Avg.

Avg %

Rec. %RSDSpike level (ug/ml) 2 2 2 2 2 2 22-methoxyethanol 1.9 1.9 1.9 2.0 2.0 1.8 1.9 1.9 96% 3%2-ethoxyethanol 1.8 1.8 1.8 1.8 1.8 1.7 1.7 1.8 88% 3%2-butoxyethanol 2.0 1.9 1.9 1.9 1.9 1.8 1.8 1.9 94% 3%propylene glycol 1.8 1.9 1.8 2.1 2.0 1.8 1.9 1.9 95% 6%ethylene glycol 1.2 1.1 1.1 1.3 1.1 0.9 0.9 1.1 53% 16%diethylene glycol 2.0 1.9 1.9 2.2 2.1 1.9 2.0 2.0 99% 6%triethylene glycol 2.2 1.9 1.8 2.1 2.0 1.8 1.9 2.0 98% 7%

Recovery and Reproducibility Evaluation-Extraction method


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• Deionized water spiked at 2 ug/ml and 10 ug/ml.

• Quantitated against multi-point calibration curve prepared in deionized water.

• 7 replicate injections of a spiked tap water sample directly into a GC-FID.

•Could not detect 2 earliest eluting compounds.

•% of spike values inconsistent at 2 ug/ml and 75-85% at 10 ug/ml.

•High %RSD values at 2 ug/ml .

Recovery and Reproducibility Evaluation-DAI Method


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Recovery and Reproducibility Evaluation-DAI Method

Injection # DAI-1 DAI-2 DAI-3 DAI-4 DAI-5 DAI-6 DAI-7 Avg. %RSD

Avg % of spike level

Spike level (ug/ml) 2 2 2 2 2 2 22-methoxyethanol2-ethoxyethanol2-butoxyethanol 1.01 0.9 0.67 0.54 0.65 0.47 0.51 0.7 30% 34%propylene glycol 2.6 3.2 1.67 1.78 1.85 1.94 1.85 2.1 26% 106%ethylene glycol 3.7 1.48 2.04 1.98 2.27 2.27 2.27 2.3 30% 114%diethylene glycol 1.41 0.91 1.67 1.05 1 0.79 0.97 1.1 28% 56%triethylene glycol 1.99 2.23 1.5 1.27 1.38 1.21 1.24 1.5 26% 77%

Injection # DAI-1 DAI-2 DAI-3 DAI-4 DAI-5 DAI-6 DAI-7 Avg. %RSD

Avg % of spike level

Spike level (ug/ml) 10 10 10 10 10 10 102-methoxyethanol2-ethoxyethanol2-butoxyethanol 6.7 7.96 7.59 8.94 8.04 8.72 7.68 7.9 9% 79%propylene glycol 8 7.48 6.8 8.47 7.57 8.24 8.02 7.8 7% 78%ethylene glycol 7.81 7.23 6.9 7.92 6.87 7.86 8.67 7.6 9% 76%diethylene glycol 7.25 7.37 8.16 7.53 8.09 8.27 9.32 8.0 9% 80%triethylene glycol 6.29 7.51 8.04 7.86 8.27 8.21 8.61 7.8 10% 78%

not detected

not detected


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Extraction method vs. DAI


10 20Time (min)

10

20

30

AU

Extract of 2 ug/ml spiked tap water

12

3

45

67

10 20Time (min)

10

20

30

pA

DAI of 2 ug/ml spiked dei. water

3 45

6 7Peaks 1 & 2 not detected


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Recovery of glycols and glycol ethers from seawater

• Recent interest in testing for propylene glycol in seawater• Propylene glycol is a constituent of the chemical dispersants used in the Gulf of Mexico oil spill

• Evaluated the extraction method for use with seawater, and seawater artificially adulterated with oil.

• The seawater used for the evaluation was obtained from the Gulf of Mexico near Galveston, TX.

Extraction of “other” water matricees


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• Two sets of spiked seawater samples were prepared • seawater spiked at 2 ug/ml • seawater containing 1 mg/ml of 80W-90 gear oil, spiked at 2 ug/ml• unspiked seawater extracted; no target analytes detected

• Average recovery values of all compounds except ethylene and triethylene glycol were >85% for both sample sets.

• No significant difference between recovery for seawater vs. seawater + oil.



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Matrix Seawater Seawater Seawater Seawater Avg. Avg. %

Rec %RSDSpike level (ug/ml) 2 2 2 22-methoxyethanol 1.78 1.82 1.76 1.72 1.8 89% 2%2-ethoxyethanol 1.82 1.82 1.76 1.76 1.8 90% 2%2-butoxyethanol 1.86 1.87 1.80 1.80 1.8 92% 2%propylene glycol 1.60 1.70 1.75 1.74 1.7 85% 4%ethylene glycol 1.31 1.48 1.40 1.22 1.4 68% 8%diethylene glycol 1.41 1.86 2.16 1.86 1.8 91% 17%triethylene glycol 0.62 0.90 1.37 0.97 1.0 48% 32%

MatrixOily

SeawaterOily

SeawaterOily

SeawaterOily

Seawater Avg. Avg. %

Rec %RSDSpike level (ug/ml) 2 2 2 22-methoxyethanol 1.82 1.90 1.84 1.84 1.85 93% 2%2-ethoxyethanol 1.85 1.90 1.88 1.82 1.86 93% 2%2-butoxyethanol 1.91 1.94 1.94 1.88 1.92 96% 1%propylene glycol 1.73 1.78 1.72 1.68 1.73 86% 2%ethylene glycol 1.26 1.44 1.35 1.34 1.35 67% 5%diethylene glycol 1.63 1.82 1.81 1.82 1.77 89% 5%triethylene glycol 0.76 0.98 0.91 0.91 0.89 45% 11%

Low recovery of triethylene glycol due to issues with GC analysis


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Glycols and glycol ethers extracted from seawater

10 20Time (min)

1

23

4

56 7


Seawater

10 20Time (min)

3

1

2

4

5

6 7

Seawater + Oil

Spiked at 2 ug/ml


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Conclusions• ENVI-Carb™ Plus can be used to extract glycols and glycol ethers from aqueous samples. This eliminates the need for DAI analysis.

• Elution from ENVI-Carb™ Plus can be achieved with an organic solvent mixture which can be solvent exchanged, concentrated down, or injected directly into a GC for analysis.

• The extraction method can achieve better accuracy, and lower detection and quantitation limits than DAI.

•Absolute recovery of ethylene glycol from water can be expected to be in the range of 50%. This issue can be addressed through the use of extracted standards for quantification.


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Conclusions• Based on the data obtained, the quantitation limit for the extraction method appears to be around 2 ug/ml. Lower quantitation limits may be obtained if the sample size extracted is increased, or further concentration is done of the sample extract.

• The extraction method can be used with seawater, however triethylene glycol cannot be accurately quantitated from seawater extracts using the current GC method.


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References1. US EPA Method 8015B, Nonhalogenated Organics Using GC-FID, December

1996, rev.2.

2. US EPA Method 1671, Volatile Organic Compounds Specific to the Pharmaceutical Manufacturing Industry by GC/FID, July 1998, rev. A.

3. Environmental Protection Agency Drinking Water Contaminant Candidate List 3 –Draft Notice, Federal Register, Vol .73, No. 35. Thursday, February 21, 2003.

4. Material Safety Data Sheet, Corexit™9500, Nalco Corp., 6/14/2005, ver. 1.6.

5. Material Safety Data Sheet, Corexit™EC9527A, Nalco Corp., 5/11/2010, ver. 2.0

6. US EPA Method 522, Determination of 1,4-Dioxane in Drinking Water by Solid Phase Extraction (SPE) and Gas Chromatography/Mass Spectrometry (GC/MS) with Selected Ion Monitoring (SIM), September 2008, ver. 1.

7. Supelco Reporter, Volume 28.3, pp. 8.

Documents

Analysis of Glycols from Drinking Water and Seawater Using